Electrode for a lithium cell

ABSTRACT

This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV 3 O 8  as one component and one or more other components consisting of LiV 3 O 8 , Ag 2 V 4 O 11 , MnO 2 , CF x , AgF or Ag 2 O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

RELATED APPLICATIONS

[0001] This application, pursuant to 37 C.F.R. 1.78(c), claims prioritybased on provisional application serial No. 60/409,440 filed on Sep. 10,2002.

CONTRACTUAL ORIGIN OF THE INVENTION

[0002] The United States Government has rights in this inventionpursuant to Contract No. W-31-109-ENG-38 between the U.S. Department ofEnergy (DOE) and The University of Chicago representing Argonne NationalLaboratory.

FIELD OF INVENTION

[0003] This invention relates to electrochemical cells and batteries andmore particularly to improved positive electrode materials fornon-aqueous lithium cells. The electrodes consist of a composite systemhaving as one component a silver-vanadium-oxide of nominal compositionAgV₃O₈. The predominant, but not exclusive, field of use is for primary(non-rechargeable) lithium batteries with particular emphasis onpowering medical devices such as cardiac pacemakers, defibrillators andmedical pumps.

BACKGROUND OF THE INVENTION

[0004] Lithium electrochemical cells and batteries are being widelyexploited as power sources for numerous applications because of theirhigh energy and power density, for example, in consumer electronics suchas laptop computers and cellular phones, in medical devices such ascardiac pacemakers and defibrillators and in electric and hybridelectric vehicles.

[0005] Silver vanadium oxides, particularly Ag₂V₄O₁₁, are well known aspositive electrode materials for primary lithium cells for poweringcardiac defibrillators in the medical industry. For example, U.S. Pat.Nos. 4,310,609 and 4,391,729 discloses the use of an electrochemicalcell having as its positive electrode a composite oxide matrixconsisting of a vanadium oxide chemically reacted with a group IB, IIB,IIIB, IVB, VB, VIB, VIIB and VIII metal, and most specifically with asilver containing compound. U.S. Pat. No. 4,391,729 also discloses amethod of making such a cathode. In addition, several scientific papersdescribing the structural and electrochemical properties of Ag₂V₄O₁₁ andAg₂V₄O_(11−x) and AgV₃O₈ have appeared in the literature, such as thatof Takeuchi et al (Journal of Power Sources, Volume 21, page 133 (1987);Leising et al (Chemistry of Materials, Volume 5, page 738 (1993));Leising et al (Chemistry of Materials, Volume 6, page 489 (1994));Garcia-Alvarado et al (Solid State Ionics, Volume 73, page 247 (1994));Kawakita et al (Solid State lonics, Volume 99, page 71 (1997)); Rozieret al, (Journal of Solid State Chemistry, Volume 134, page 294 (1997)).Moreover, lithium vanadium oxide electrodes, such as Li_(1.2)V₃O₈, arealso well known for their good electrochemical properties inrechargeable or secondary lithium cells. For example, U.S. Pat. No.5,039,582 discloses the use of an amorphous form of LiV₃O₈ as a positiveelectrode in a lithium cell, and U.S. Pat. No. 5,336,572 discloses theuse of M_(x)V₃O₈ positive electrodes for lithium cells, where M is amonovalent or multivalent metal cation. In addition, numerous researchpapers on the structural and electrochemical properties of Li_(x)V₃O₈materials have been written, such as that of Wadsley et al (ActaCrystallographica, Volume 10, page 261 (1957)); de Picciotto et al(Solid State Ionics, Volume 62, page 297 (1993); Panera et al (Journalof the Electrochemical Society, Volume 130, page 1225 (1983)); West etal (Journal of the Electrochemical Society, Volume 143, page 820(1996)). Spahr et al has disclosed the use of NaV₃O₈ as a cathode in alithium cell (Journal of the Electrochemical Society, Volume 145, page421 (1998)).

[0006] A problem that is encountered with state-of-the-art Ag₂V₄O₁₁cathodes in lithium cells is the deterioration of electrochemicalperformance, particularly the ability of the cells to deliver acceptablepulse power before the cell has reached the end of its expected calendarand operating life. It can therefore be readily understood that suchlimitations of Li/Ag₂V₄O₁₁ cells are of great concern when used to powercardiac defibrillators in the human body. Such limitations negativelyaffect product reliability and necessitate a continual monitoring of thecells while implanted in patients to ensure a timely replacement of thecells before they prematurely reach the end of discharge. There istherefore a great need to improve the electrochemical properties andoperating life of silver-vanadium-oxide electrodes for lithium cells andbatteries, particularly for use in life-supporting medical devices, suchas cardiac defibrillators.

SUMMARY OF THE INVENTION

[0007] This invention relates to a positive electrode for anelectrochemical cell or battery, and to an electrochemical cell orbattery; the invention relates more specifically to an improved positiveelectrode for a non-aqueous lithium cell or battery when the electrodeis used therein, the positive electrode comprising a composite metaloxide containing AgV₃O₈ as one component and one or more componentsselected from LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O to increasethe energy density of the cell optionally in the presence of silverpowder and/or silver foil to assist in current collection at theelectrode and to improve the power capability of the cell or battery.When the composite electrode consists of AgV₃O₈ and LiV₃O₈ components,the electrode has the general formula xAgV₃O₈.(1−x)LiV₃O₈ (oralternatively Ag_(x)Li_(1−x)V₃O₈). The invention extends to includesubstituted Ag_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode compounds in whichthe limits of x and y are 0<x<1, 0<y<1.5, respectively, and where M is amonovalent or multivalent ion of one or more transition metals and mostpreferably one or more of Ti, Y, Zr, Nb and Mo ions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention consists of certain novel features and acombination of parts hereinafter fully described, illustrated in theaccompanying drawings, and particularly pointed out in the appendedclaims, it being understood that various changes in the details may bemade without departing from the spirit, or sacrificing any of theadvantages of the present invention.

[0009]FIG. 1 depicts a schematic illustration of a LiV₃O₈ or AgV₃O₈structure;

[0010]FIG. 2 depicts the powder X-ray diffraction pattern of AgV₃O₈;

[0011]FIG. 3 depicts the powder X-ray diffraction pattern of LiV₃O₈;

[0012]FIG. 4 depicts the powder X-ray diffraction pattern of axAgV₃O₈.(1−x)LiV₃O₈ composite;

[0013]FIG. 5 depicts the powder X-ray diffraction pattern of Ag₂V₄O₁₁;

[0014]FIG. 6 depicts the powder X-ray diffraction pattern of aAgV₃O₈/Ag₂V₄O₁₁ composite

[0015]FIG. 7 depicts the electrochemical (pulsed current) profile forthe discharge of a Li/AgV₃O₈ cell;

[0016]FIG. 8 depicts the electrochemical (pulsed current) profile forthe discharge of a Li/LiV₃O₈ cell;

[0017]FIG. 9 depicts the electrochemical (pulsed current) profile forthe discharge of a Li/xAgV₃O₈.(1−x)LiV₃O₈ cell;

[0018]FIG. 10 depicts the electrochemical (pulsed current) profile forthe discharge of a Li/AgV₃O₈, MnO₂ cell;

[0019]FIG. 11 depicts the electrochemical (pulsed current) profile forthe discharge of a Li/AgV₃O₈, Ag₂O cell;

[0020]FIG. 12 depicts the electrochemical (pulsed current) profile forthe discharge of a Li/AgV₃O₈, Ag cell;

[0021]FIG. 13 depicts a schematic illustration of an electrochemicalcell; and

[0022]FIG. 14 depicts a schematic illustration of an example of abattery employing the cells of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] State-of-the-art cardiac defibrillators are powered by lithiumbatteries in conjunction with electrolytic capacitors. The batteriescontain a metallic lithium negative electrode, a silver-vanadium oxidepositive electrode of composition Ag₂V₄O₁₁, and a non-aqueous liquidelectrolyte consisting of a lithium salt such as LiAsF₆ dissolved in anorganic solvent, such as a 50:50 mixture of propylene carbonate anddimethoxyethane. Li/Ag₂V₄O₁₁ cells discharge by an electrochemicalprocess that involves lithium insertion into the crystal lattice ofAg₂V₄O₁₁ with a simultaneous reduction of the silver ions and theirconcomitant extrusion from the crystal lattice. Thereafter, lithiuminsertion is accompanied by the reduction of the vanadium ions withinthe structure, ideally from V⁵⁺ to V⁴⁺. Thus, the reaction can bebroadly defined in the ideal case as taking place in two main steps:

Li+Ag₂V₄O₁₁→Li₂V₄O₁₁+2Ag   (Step 1: Silver displacement)

xLi+Li₂V₄O₁₁→Li_(2+x)V₄O₁₁ (x _(max)≈5)   (Step 2: Lithium insertion)

[0024] One of the major limitations of Li/Ag₂V₄O₁₁ cells is that theylose their capability of providing the necessary power particularlyafter the reaction described in Step 1 has occurred, and when cells areallowed to stand for prolonged periods of time. It is believed that thisloss in power may be attributed, at least in part, to the Ag₂V₄O₁₁positive electrode, and in particular, that it may be attributed to thefact that at the end of Step 1, a metastable phase of compositionLi₂V₄O₁₁ is formed. This metastability is reflected by the fact that ithas not been possible to synthesize a Li₂V₄O₁₁ phase that isisostructural with Ag₂V₄O₁₁ by independent chemical methods in thelaboratory. Attempts to synthesize a Li₂V₄O₁₁ phase in the laboratory,for example, by reacting Ag₂V₄O₁₁ with n-butyllithium, have failed;these attempts have always yielded other stable lithium-vanadium-oxidephases such as LiVO₃ and LiV₃O₈. This finding indicates that the powerfade may at least be partly attributed to a decay of the “Li₂V₄O₁₁”phase that is generated electrochemically during Step 1 into other morestable lithium-vanadium-oxide compounds.

[0025] This invention addresses this problem and advocates the use ofalternative electrode materials for Ag₂V₄O₁₁ electrodes, andparticularly composite electrodes in which AgV₃O₈ is one component ofthe electrode. In one embodiment of the invention, the electrode is acomposite electrode of AgV₃O₈ and LiV₃O₈ having the general formulaxAgV₃O₈.(1−x)LiV₃O₈ (or alternatively, Ag_(x)Li_(1−x)V₃O₈) for 0<x<1.Because the of AgV₃O₈ and LiV₃O₈ are similar, it is envisaged that asolid solution or mixture of phases may exist between AgV₃O₈ and LiV₃O₈,the latter phase being known to be an extremely stable material and easyto synthesize by chemical methods in the laboratory, unlike hypothetical“Li₂V₄O₁₁”. The advantage of such a system is that after displacement orextrusion of the Ag from the Ag_(x)Li_(1−x)V₃O₈ structure or compositestructure (analogous to Step 1 given for Ag₂V₄O₁₁ above) the compound,LiV₃O₈, is generated that is stable in the cell environment;furthermore, it is known that the LiV₃O₈ thus formed, can accommodateadditional lithium without disruption of the V₃O₈ framework to acomposition Li_(1+y)V₃O₈, where y_(max)=4. Thus for an undopedelectrode, the two main discharge reactions for an Ag_(x)Li_(1−x)V₃O₈electrode would ideally be (by analogy to Steps 1 and 2 above):

xLi+Ag_(x)Li_(1−x)V₃O₈→LiV₃O₈ +xAg   (Step 1: Silver displacement)

yLi+LiV₃O₈→Li_(1+y)V₃O₈ (y _(max)=4)   (Step 2: Lithium insertion)

[0026] It will be appreciated by those skilled in the art, that inpractice when AgV₃O₈ and LiV₃O₈ compounds are synthesized, theirstoichiometries may vary slightly from their numerically ideal formulae.For example, it has been well established that the thermodynamicallystable stoichiometry of the lithium-vanadium-oxide compound whensynthesized at approximately 600° C. is Li_(1.2)V₃O₈. The 3 vanadiumions of the formula unit reside in either octahedral or square-pyramidalsites (shown as connected polyhedra in FIG. 1). Of the 1.2 lithium ions,1.0 Li ions occupy octahedral sites (shown as black dots in FIG. 1) andthe remaining 0.2 Li ions partially occupy tetrahedral sites (not shownin FIG. 1). It is therefore possible that small deviations instoichiometry may also occur for AgV₃O₈. This invention therefore allowsfor such deviations in stoichiometry and the simplified formulaxAgV₃O₈.(1−x)LiV₃O₈, alternatively Ag_(x)Li_(1−x)V₃O₈, is merely usedfor convenience.

[0027] In a second embodiment, this invention includes substitutedAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode compounds in which the limits ofx and y are 1<x<1, 0<y<1.5, respectively, and where M is a monovalent ormultivalent ion of one or more transition metals. Such metalsubstitutions in LiV_(3−y)M_(y)O₈ compounds, in which M can, forexample, be selected typically from one or more of Ti, Y, Zr, Nb and Moas already disclosed in U.S. Pat. No. 6,322,928, can be used to impartgreater stability to the LiV₃O₈ electrode structure. It is believed thatsuch substitutions could also be used to stabilize the V₃O₈ framework ofthe Ag_(x)Li1−_(x)V_(3−y)M_(y)O₈ electrodes of this invention.

[0028] A significant advantage of using xAgV₃O₈.(1−x)LiV₃O₈ orAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode is that it is possible to varythe Ag:Li ratio in the initial electrode, thus providing the opportunityto tailor and optimize the gravimetric and volumetric capacities of theelectrode and hence the gravimetric and volumetric energy densities ofthe lithium cell. For example, the theoretical gravimetric andvolumetric capacities for AgV₃O₈ are 345 mAh/g and 1518 mAh/ml,respectively, whereas for LiV₃O₈ the theoretical and volumetriccapacities are 373 mAh/g and 1350 mAh/ml, respectively (see Table 1).Furthermore, because it is believed that Ag in the crystal structure mayhinder Li⁺-ion transport in the electrode during cell operation, it isfurther believed that the power capability of the xAgV₃O₈.(1−x)LiV₃O₈ orAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode will be achieved by fine-tuningthe Ag:Li ratio in the initial structure.

[0029] In a third embodiment, the composite electrode consists of theAgV₃O₈, xAgV₃O₈.(1−x)LiV₃O₈ or Ag_(x)Li_(1−x)V_(3−y)M_(y)O₈ componentwith one or more components selected from Ag₂V₄O₁₁, MnO₂, CF_(x), AgFand/or Ag₂O to improve the energy density of the lithium cell. In thisrespect, blended (composite) electrodes comprised of Ag₂V₄O₁₁ and CF_(x)are known in the art. Improvements in the electrochemical properties ofthe electrodes and cells of the present invention can be obtained byoptionally blending the electrodes with Ag₂V₄O₁₁, MnO₂, CF_(x), AgFand/or Ag₂O.

[0030] Table 1 demonstrates from theoretical values how, in principle,the addition of one (or more) components to a AgV₃O₈ electrode canincrease the energy density of the cell either in terms of specificenergy density (Wh/kg) and/or volumetric energy density (Wh/l). Thevoltage of each lithium cell provided in Table 1 reflects the averageopen circuit voltage (OCV) of the cell during discharge, as determinedfrom the OCV values that were recorded after each pulse, to an endvoltage of 1.7 V. TABLE 1 Electrochemical and physical properties ofvarious electrode components Th. Th. Li Cap. ρ Cap. Th. Energy Electrodeuptake (mAh/ (g/ (mAh/ Voltage Dens. Material (max) g) ml) ml) (OCV)Wh/kg Wh/l Primary Component AgV₃O₈ 5 345 4.40 1518 2.65 914 4022Secondary Components LiV₃O₈ 4 373 3.62 1350 2.70 1007 3645 MnO₂ 1 3084.83 1487 2.85 878 4241 Ag₂V₄O₁₁ 7 315 4.94 1556 2.64 832 4110 CF_(x)0.6 687 2.60 1786 ˜3.0 2061 5359 AgF 1 211 5.85 1234 ˜3.3 696 4071 Ag₂O2 231 7.29 1683 ˜3.0 693 5052

[0031] In a fourth embodiment, the electrodes of this invention aremixed with Ag powder which serves as an additional current collector tothe carbon powder (typically acetylene black) which is conventionallypresent with metal oxide electrodes in lithium cells. Furthermore, it isbelieved that the Ag powder acts as nucleating sites for the silvermetal that is extruded from the AgV₃O₈, Ag₂V₄O₁₁, AgF and Ag₂Ocomponents during discharge, thereby enhancing the current collection atthe electrode and the power capability of the cell. Alternatively, whenlaminated electrodes are used, silver foil is used as the currentcollector onto which the electrochemically active electrode powder iscast. This invention therefore extends to include silver currentcollectors for silver vanadium oxide electrodes, in general, forapplication in lithium electrochemical cells and batteries.

[0032] The negative electrodes of the electrochemical cells of thepresent invention may be selected from any suitable lithium-containingcompound known in the art, for example, metallic lithium, lithiumalloys, lithium intermetallic compounds and lithiated carbon, such aslithiated graphite Li_(x)C₆ in which x can reach a typical value of 1.Preferably, the negative electrode is metallic lithium.

[0033] Likewise the non-aqueous electrolyte may be selected from anysuitable electrolyte salts and solvents that are known in the art.Examples of well known salts are LiCl₄, LiAsF₆, LiPF₆, LiBF₄ andLiB(C₂O₄)₂, and typical electrolyte solvents are propylene carbonate,ethylene carbonate, diethyl carbonate, dimethyl carbonate, diethylether, dimethoxyethane and the like.

[0034] The principles of this invention are provided in the followingexamples.

[0035] Synthesis and Preparation of Electrode Materials

EXAMPLE 1

[0036] AgV₃O₈ was prepared by direct reaction of stoichiometric amountsof NH₄VO₃ and AgNO₃ powders under oxygen at 530° C. The powder X-raydiffraction pattern of the resulting product is shown in FIG. 2.

EXAMPLE 2

[0037] LiV₃O₈ was prepared by direct reaction of stoichiometric amountsof NH₄VO₃ and Li₂CO₃ powders in air at 550° C. The powder X-raydiffraction pattern of the resulting product is shown in FIG. 3.

EXAMPLE 3

[0038] A composite electrode powder xAgV₃O₈.(1−x)LiV₃O₈ in which x=0.5was prepared by milling the two separate powders of AgV₃O₈ and LiV₃O₈under acetone (or methanol) for 3 days, followed by filtering and dryingthe product under vacuum at room temperature. The powder X-raydiffraction pattern of the resulting product is shown in FIG. 4.Although the two components of this example were mixed in a 50/50 weightratio, other variations are specifically included in the invention.

EXAMPLE 4

[0039] Ag₂V₄O₁₁ was prepared by direct reaction of stoichiometricamounts of NH₄VO₃ and AgNO₃ powders in air at 500° C. The powder X-raydiffraction pattern of the resulting product is shown in FIG. 5.

EXAMPLE 5

[0040] Composite electrode powders were prepared by using intimatelymixed blends of the following materials:

[0041] 1. AgV₃O₈:Ag₂V₄O₁₁ (95:5 ratio by weight);

[0042] 2. AgV₃O₈:MnO₂ (50:50 ratio by weight);

[0043] 3. AgV₃O₈/Ag₂O (97:3 ratio by weight);

[0044] 4. AgV₃O₈/Ag (95:5 ratio by weight);

[0045] For these composite electrodes, the AgV₃O₈ and Ag₂V₄O₁₁ powderswere prepared as described in Examples 1 and 4, respectively. The MnO₂was obtained as an electrolytic manganese dioxide (EMD) from Chemetals.The Ag₂O and Ag powders were supplied by Aldrich.

[0046] Electrochemical Evaluation

[0047] In general, the lithium cells were fabricated as follows.Positive electrode laminates were made by the following generalprocedure. The active electrode powders were sifted to <40 μm, mixedwith 8 w/o carbon (acetylene black and SFG6) and 8 w/o polyvinlyidinedifluoride (PVDF) binder and cast onto an Al foil with NMP dilutant. Thecast laminate was subsequently dried at 70°, and placed into a vacuumoven overnight. Coin cells of size 2032 (2.0 cm diameter, 3.2 mm high)were used for the electrochemical evaluations. The positive electrodeconsisted of a 1.6 cm diameter disc, punched from the laminate; acorresponding disc of metallic lithium, punched from lithium foil servedas the negative electrode. Electrodes were insulated from one another bya porous Celgard separator. The electrolyte was 1 M LiAsF₆ dissolved ineither propylene carbonate (PC) or a 50:50 mixture of PC anddimethoxyethane (DME). The electrochemical data were collected frompulsed-current discharge tests (one 10-second pulse of 1 mA/cm² everyfifteen minutes) of the button cells. Cells were discharged under pulseto an end voltage of at least 1.5 V. Several cells with differentpositive electrode materials were constructed for which electrochemicaldata were collected as defined by the following examples:

EXAMPLE 6

[0048] The 10-second pulse discharge profile of a lithium cellcontaining the AgV₃O₈ electrode of Example 1 is shown in FIG. 7.

EXAMPLE 7

[0049] The 10-second pulse discharge profile of a lithium cellcontaining the LiV₃O₈ electrode of Example 2 is shown in FIG. 8.

EXAMPLE 8

[0050] The 10-second pulse discharge profile of a lithium cellcontaining a composite xAgV₃O₈.(1−x)LiV₃O₈ electrode of Example 3 isshown in FIG. 9.

EXAMPLE 9

[0051] The 10-second pulse discharge profiles of lithium cellscontaining the composite electrodes AgV₃O₈/MnO₂; AgV₃O₈/Ag₂O; andAgV₃O₈/Ag of Example 5 are shown in FIGS. 10, 11 and 12, respectively.

[0052] The total capacities of each of the electrodes in Examples 6-9,delivered to an end voltage of 1.7 V and the corresponding energydensities of the lithium cells, are summarized in Tables 2 and 3, whichdemonstrates the utility of the electrode materials of this invention.

EXAMPLE 10

[0053] Ten-second pulse discharge profiles of lithium button cellscontaining AgV₃O₈ and Ag₂V₄O₁₁ electrodes with Al and Ag foil currentcollectors were collected in the same manner as described in theforegoing examples. The results of these experiments are summarized inTable 3; the data show how the specific capacity of both types of silvervanadium oxide electrode, i.e., not only AgV₃O₈but also Ag₂V₄O₁₁, can besignificantly improved by changing the current collector at the positiveelectrode from aluminum foil to silver foil, which also results in asignificant improvement in the energy density of the lithium cell. TABLE2 Performance data of various electrodes Specific Capacity EnergyDensity Electrode Material (mAh/g) (mWh/cm³) AgV₃O₈ 284 3049 LiV₃O₈ 2792325 xAgV₃O₈.(1 − x)LiV₃O₈ 218 2032 AgV₃O₈/MnO₂ 241 2822 AgV₃O₈/Ag₂O 2442681 AgV₃O₈/Ag 265 3097

[0054] TABLE 3 Performance data of AgV₃O₈ and Ag₂V₄O₁₁ electrodes withAg and Al foil current collectors Current Specific Capacity EnergyDensity Electrode Material Collector (mAh/g) (mWh/cm³) AgV₃O₈ Al 2482666 AgV₃O₈ Ag 348 3799 Ag₂V₄O₁₁ Al 286 3474 Ag₂V₄O₁₁ Ag 306 3652

[0055] This invention, therefore, relates to positive electrodes andcurrent collectors for a non-aqueous electrochemical lithium cell, asshown schematically in FIG. 13, the cell represented by the numeral 10having a negative electrode 12 separated from a positive electrode 16 byan electrolyte 14, all contained in an insulating housing 18 withsuitable terminals (not shown) being provided in electronic contact withthe negative electrode 12 and the positive electrode 16. Negativeelectrode 12 may be LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O withmetallic lithium preferred. Binders and other materials normallyassociated with both the electrolyte and the negative and positiveelectrodes are well known in the art and are not described herein, butare included as is understood by those of ordinary skill in this art.FIG. 14 shows a schematic illustration of one example of a battery inwhich two strings of electrochemical lithium cells, described above, arearranged in parallel, each string comprising three cells arranged inseries.

[0056] While particular embodiments of the present invention have beenshown and described, it will be appreciated by those skilled in the artthat changes, modifications and improvements may be made withoutdeparting from the true spirit and scope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A positive electrode fora non-aqueous lithium cell comprising a composite metal oxide containingAgV₃O₈ as one component, and one or more additional components selectedfrom LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O.
 2. The positiveelectrode of claim 1, wherein the additional components are selectedfrom LiV₃O₈ and Ag₂V₄O₁₁.
 3. The positive electrode of claim 2, whereinthe composite metal oxide is a solid solution of xAgV₃O₈.(1−x)LiV₃O₈ orAg_(x)Li_(1−x)V₃O₈.
 4. The positive electrode of claim 3, wherein thecomposite metal oxide is Ag_(x)Li_(1−x)V_(3−y)M_(y)O₈ in which 0<x<1 and0<y<1.5, and in which M is one or more monovalent or multivalenttransition metals.
 5. The positive electrode of claim 4, wherein the Mions are selected from one or more of Ti, Y, Zr, Nb and Mo ions.
 6. Thepositive electrode of claim 1 in which the electrode contains a silverpowder or silver foil current collector.
 7. The positive electrode ofclaim 4 in which the electrode contains a current collector of silverpowder or silver foil or both.
 8. A non-aqueous lithium electrochemicalcell comprising a negative electrode, an electrolyte and a positiveelectrode, the positive electrode comprising a composite metal oxidecontaining AgV₃O₈ as one component, and one or more additionalcomponents selected from LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O. 9.The non-aqueous lithium electrochemical cell of claim 8 in which thepositive electrode contains a silver powder or silver foil currentcollector.
 10. The non-aqueous lithium electrochemical cell of claim 8in which the negative electrode is selected from metallic lithium,lithium alloys, lithium intermetallic compounds and lithiated carbon.11. The non-aqueous lithium electrochemical cell of claim 8 in which thenegative electrode is metallic lithium.
 12. The non-aqueous lithiumelectrochemical cell of claim 8, wherein the cathode is selected fromLiV₃O₈ and Ag₂V₄O₁₁.
 13. The non-aqueous lithium electrochemical cell ofclaim 8, wherein the composite metal oxide in a solid solution ofxAgV₃O₈.(1−x)LiV₃O₈ or Ag_(x)Li_(1−x)V₃O₈.
 14. The non-aqueous lithiumelectrochemical cell of claim 8, wherein the composite metal oxide isAg_(x)Li_(1−x)V_(3−y)M_(y)O₈, in which 0<x<1 and 0<y<1.5, and in which Mis one or more monovalent or multivalent transition metals.
 15. Thenon-aqueous lithium electrochemical cell of claim 8, wherein the M ionsare selected from one or more of Ti, Y, Zr, Nb and Mo ions.
 16. Thenon-aqueous lithium electrochemical cell of claim 14 in which theelectrode contains a silver powder or silver foil current collector. 17.The positive electrode of claim 16 in which the electrode contains acurrent collector of silver powder or silver foil or both.
 18. Anon-aqueous lithium battery comprising a plurality of electrochemicalcells, electrically connected, each cell comprising a negativeelectrode, an electrolyte and a positive electrode, the positiveelectrode comprising a composite metal oxide containing AgV₃O₈ as onecomponent, and one or more additional components selected from LiV₃O₈,Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O.
 19. A non-aqueous lithium batteryof claim 18, in which the positive electrode of each electrochemicalcell contains a silver powder or silver foil current collector.
 20. Anon-aqueous lithium battery of claim 18, in which the negative electrodeof each electrochemical cell is selected from metallic lithium, lithiumalloys, lithium intermetallic compounds and lithiated carbon.
 21. Anon-aqueous lithium battery of claim 18, in which the negative electrodeof each electrochemical cell is metallic lithium.
 22. The non-aqueouslithium electrochemical battery of claim 18, wherein the cathode isselected from LiV₃O₈ and Ag₂V₄O₁₁.
 23. The non-aqueous lithiumelectrochemical battery of claim 18, wherein the composite metal oxidein a solid solution of xAgV₃O₈.(1−x)LiV₃O₈ or Ag_(x)Li_(1−x)V₃O₈. 24.The non-aqueous lithium electrochemical battery of claim 18, wherein thecomposite metal oxide is Ag_(x)Li_(1−x)V_(3−y)M_(y)O₈, in which 0<x<1and 0<y<1.5, and in which M is one or more monovalent or multivalenttransition metals.
 25. The non-aqueous lithium electrochemical batteryof claim 18, wherein the M ions are selected from one or more of Ti, Y,Zr, Nb and Mo ions.
 26. The non-aqueous lithium electrochemical batteryof claim 24 in which the electrode contains a silver powder or silverfoil current collector.
 27. A positive electrode for a non-aqueouslithium cell comprising AgV₃O₈ and a Ag current collector.
 28. Thepositive electrode of claim 27, wherein the Ag current collector ispowder or foil.
 29. A positive electrode for a non-aqueous lithium cellcomprising Ag₂V₄O₁₁ and a Ag current collector.
 30. The positiveelectrode of claim 29, wherein the Ag current collector is powder orfoil.
 31. A non-aqueous lithium electrochemical cell comprising anegative electrode, an electrolyte and a positive electrode, thepositive electrode comprising AgV₃O₈ and a Ag current collector.
 32. Thenon-aqueous lithium electrochemical cell of claim 31, wherein thecurrent collector is powder or foil.
 33. A non-aqueous lithium batterycomprising a plurality of electrochemical cells electrically connected,each cell comprising a negative electrode, an electrolyte and a positiveelectrode, the positive electrode comprising AgV₃O₈ and a Ag currentcollector.
 34. The non-aqueous lithium electrochemical cell of claim 33,wherein the current collector is powder or foil.